Multicast Routing, Modulation Level, and Spectrum Assignment in Elastic Optical Networks - A Genetic Algorithm and Light-hierarchy Approach

Multicast transmission in elastic optical networks (EON) is a central problem. When EON admits modulation schemes, the multicast problem is called multicast routing and modulation level and spectrum assignment (MRMLSA). Whenever EON supports light-splitting capabilities, the structure of the MRMLSA solution is a light-tree. Conversely, when EON does not support light-splitting, the multicast request is divided into several unicast requests, one per destination. In the latter case, the structure of solutions is a light-path that inefficiently uses transponders compared to a light-tree. Note that light paths are acyclic structures, which means they can only pass through the same node once. A recent alternative proposes a Light-hierarchy (LH) structure that relaxes this constraint so that a light-path can pass more than once through a node to get all node destinations. Literature has proposed integer linear programming (ILP) based approaches to solve MRMLSA considering LH structure; however, multicast routing is an NP-complete problem, so this paper proposes scalable solutions based on Heuristic and Genetic Algorithm (GA) for the LH-MRMLSA problem. Numerical simulations were performed on different test instances to analyze the proposals. The results show that the GA based on permutations can compute efficient solutions compared to the Heuristic but at a higher computational time.